Study on Effect of Countermeasure for Fall from Scaffolds in Japan

Introduction

Frequent fall accidents are severe problems encountered in construction industries, with approximately 40% of fatal accidents during construction attributed to workers’ falls, as shown in Figure 1. In Japan, countermeasures for falls from scaffolds had been strengthened through systematization in official guidelines. Although these efforts reduced the rate of scaffold-related fatal falls, the overall percentage remains high—an issue that elevated possible countermeasures to the main agenda of the 11th Labour Accidents Prevention Plan in Japan.

To develop additional preventive measures for scaffold-related falls, the Japanese Ministry of Health, Labour, and Welfare established a committee at our institute. This committee was mandated to investigate the safety regulations applied in construction industries overseas and to evaluate various Japanese construction methods in accordance with present safety guidelines.

The results and discussion show that workers sometimes fall from the space between guardrails and work platforms. Preventing falls of this nature necessitates compressing this space. The experiments conducted by the committee also indicate that scaffold sheeting, which is used to cover scaffolds and is widely used in Japan, as shown in Figure 2, contributes to worker safety; that is, it protects them from falls [1]. Therefore, the effect of scaffold sheeting was experimentally examined.

On the basis of the results and discussion, the Occupational Safety and Health Regulations were amended in 2009. In this study, effects of these measures were investigated.

Figure 1. Number of fatal accidents in Japanese construction industry in 2009.

Figure 2. Scaffolds covered with sheeting.

Methodology

The effect of scaffold sheeting was experimentally examined using a human dummy. Table 1 lists the experimental cases. An experiment with a used plastic sheet (Case 8) was carried out to determine the strength of a deteriorated sheet. In all the experiments, the human dummy did not fall from the scaffolds, leading to the conclusion that plastic sheets are effective fall protection measures.

Table 1. Experimental cases.

Amendment of regulations

Nonetheless, occasional falls from the space between work platforms and scaffold sheeting continued to occur. Such incidents are attributed to space expansion stemming from the pressure exerted by workers’ weights, as shown in Figure 3. When workers reach down to the sides of scaffolds to conduct repairs, they push the sheeting to make room for movement, thereby widening the space between the platform and the sheet. To prevent workers from suffering fall accidents, the Occupational Safety and Health Regulations were amended in 2009, as shown in Figure 4. In this study, the effects of the amended regulations were investigated on the basis of the accident reports provided by the Labour Standard Office of Japan.

Figure 3. A worker making room for movement by pushing the sheeting.

Figure 4. Fall protection as outlined in the amended regulations.

Advances Guardrail

In Japan, the advanced guardrail installation method is occasionally used for protection from falls from scaffolds, as shown in Figure 5. The MHLW aims to spread the use of this method through their safety guidelines, which was amended in 2009. Figure 6 shows the installation method for an advanced guardrail.

In the method, the upper guardrails are always set from the lower platforms using the advanced guardrails, as shown in Figure 6, and the workers are always protected from a fall by the advanced guardrails at the top of the previously erected scaffolds.

Figure 5. Scaffolds assembled by Advanced Guardrail Installation Method.

Figure 6. Advanced Guardrail Installation Method.

Results

Labor accidents, in which workers are killed or required to rest for more than three days because of injury, are documented by the Labour Standard Office. These injury accident reports were examined in relation to falls from scaffolds [2]. Table 2 shows the changes in the number of injury accidents from 2007 to 2011. From 2008 to 2009, the number of scaffold-related fall accidents drastically decreased from 1,227 to 828. This finding confirms the effectiveness of the amended regulations and guidelines in decreasing accident frequency.

Table 2. Changes in the number of injury accidents from 2007 to 2011 (persons).

Discussion

The injury accident reports were also analyzed to determine other factors that contribute to falls from scaffolds. Figure 7 shows the classification of factors that caused fall accidents in 2011. Approximately 90% of the accidents (378 persons) occurred in work environments characterized by illegal conditions. Most of these fall accidents can be prevented by compliance with the amended regulations. Additionally, 42.2% of the accidents (38 + 140 = 178 persons) occurred because of unsafe acts. Aside from compliance with the amended regulations, therefore, risk assessment or safety education should be executed more.

Figure 7. Factors that contribute to fall accidents from scaffolds.

Conclusions

The developments on safety in Japan’s construction industry are summarized as follows.

• 1. The Occupational Safety and Health Regulations were amended in 2009 to prevent scaffoldrelated fall accidents.
• 2. Guidelines for advanced guardrail installation method were also amended in 2009.
• 3. The effects of the amended regulations were investigated on the basis of injury accident reports.
• 4. Most fall accidents from scaffolds can be prevented through compliance with the amended regulations.
• 5. Among the total number of accidents, 42.2% occurred as a result of unsafe acts, indicating the importance of awareness programs, such as risk assessment or safety education.

References

• 1. K. Ohdo, Y. Toyosawa, S. Takanashi, Y. Hino, & H. Takahashi (2009). Study on Mitigation of Fall Risk from Scaffolds in Construction Industry. Proceedings of the Tenth International Conference on Structural Safety and Reliability, pp. 187192, Osaka, Kansai University.
• 2. Ministry of Health, Labour, and Welfare, Japan. (2013). Reports of the committee for investigation of the effect of the fall protection from the scaffolds. Retrieved 6 March 2014, from http://www.mhlw.go.jp/stf/shingi/2r98520000035cmratt/2r98520000035co8.pdf (in Japanese).